also do the electronic noise makers get rid of the litte critters?
NO to both parts of your question. You will be much better off if you find how they are getting in.
Fiberglass insulation wo'nt discourage rats, in fact rodents love it to build their nests with it. As far as the electronic sirens go I've heard that they do work, but I'm not sure how good they actually do. I do know that you cant use them if you have hamsters or guenea pigs for pets. Hope this helped you out, good luck!
